berkelium (Bk)

A synthetic, radioactive, metallic element
of the actinide series; also a transuranic
element. It was first made in 1949 by alpha
particle bombardment of americium-241
by S. G. Thompson and coworkers at the University of California at Berkeley
(after which it is named). It can also be prepared by bomabrding curium-244
with neutrons. Less than a gram is made
each year. Nine isotopes are known the most
stable of which is 247Bk (half-life 1.4 × 103
yr).